/*
 * Copyright [2013-2021], Alibaba Group Holding Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.polardbx.executor.mpp.util;

import com.google.common.collect.AbstractIterator;

import java.util.Iterator;

import static java.util.Objects.requireNonNull;

public class MppIterators {

    public static <T> Iterator<T> closeWhenExhausted(Iterator<T> iterator, AutoCloseable resource) {
        requireNonNull(iterator, "iterator is null");
        requireNonNull(resource, "resource is null");

        return new AbstractIterator<T>() {
            @Override
            protected T computeNext() {
                if (iterator.hasNext()) {
                    return iterator.next();
                } else {
                    try {
                        resource.close();
                    } catch (Exception e) {
                        throw new RuntimeException(e);
                    }
                    return endOfData();
                }
            }
        };
    }
}
